genus of low, branchy desert shrubs, 1914, from Modern Latin (1737) from Greek ephedra, a name given by Pliny to the horsetail, literally "sitting upon," from fem. of ephedros "sitting or seated upon; sitting at or near," from epi "on" (see epi-) + hedra "seat, base, chair; face of a geometric solid" (see sedentary). The reason for the name is not known.